This application is related to U.S. patent application filed as Ser. No. 10/955,325 filed on even date herewith, hereby expressly incorporated by reference herein.
1. Field of the Invention
The present invention relates to a method and apparatus for flowing a fluid over a substrate in a processing system and, more particularly, to a method and apparatus for controlling the velocity field of the fluid flow over the substrate in a processing system.
2. Description of Related Art
During the fabrication of semiconductor devices for integrated circuits (ICs), a critical processing requirement for processing semiconductor devices is cleanliness. The processing of semiconductor devices includes vacuum processing, such as etch and deposition processes whereby material is removed from or added to a substrate surface, as well as atmospheric processing, such as wet cleaning whereby contaminants or residue accumulated during processing are removed. For example, the removal of residue, such as photoresist, hardened photoresist, post-etch residue, and post-ash residue subsequent to the etching of features, such as trenches or vias, can utilize dry plasma ashing with an oxygen plasma followed by wet cleaning.
Until recently, dry plasma ashing and wet cleaning were found to be sufficient for removing residue and contaminants accumulated during semiconductor processing. However, recent advancements for ICs include a reduction in the critical dimension for etched features below a feature dimension acceptable for wet cleaning, such as a feature dimension below 45 to 65 nanometers, as well as the introduction of new materials, such as low dielectric constant (low-k) materials, which are susceptible to damage during plasma ashing.
Therefore, at present, interest has developed for the replacement of dry plasma ashing and wet cleaning. One interest includes the development of dry cleaning systems utilizing a supercritical fluid as a carrier for a solvent, or other residue removing composition. Post-etch and post-ash cleaning are examples of such systems. Other interests include other processes and applications that can benefit from the properties of supercritical fluids, particularly of substrates having features with a dimension of 65 nm, or 45 nm, or smaller. Such processes and applications may include restoring low dielectric films after etching, sealing porous films, drying of applied films, depositing materials, as well as other processes and applications. At present, the inventors have recognized that conventional processing systems offer insufficient control of the flow, or velocity field, of the supercritical fluid over the substrate to be treated and, furthermore, such systems suffer from particulate contamination.